Participants will be studied in a randomized trial of 240 mg of Ginkgo biloba as compared to placebo in healthy men and women, at least 75 years old. The trial will last approximately 8 years. The intervention will be considered unsuccessful in those participants who succumb to dementia, including Alzheimer's Disease and vascular dementia. There are four clinical centers: Pittsburgh, PA; Hagerstown, MD; Winston-Salem, NC; and Sacramento, CA; and a Coordinating Center at the University of Washington, Seattle. There will be a clinic visit every 6 months to determine morbidity, mortality and change in cognition that will include repeat of ADAS, CDR, and 10 battery neuropsychological evaluation and informant interview. The primary endpoint is dementia, specifically Alzheimer's disease, secondary endpoint will include the incidence of vascular disease, changes in cognitive function scores over time, total mortality and changes in functional status. The diagnosis of dementia will be based on neuropsychological testing, neurological exam, MRI, functional measurements, and review by a central adjudication committee and classified by DSM IV, NINCDS criteria and ADRTC criteria for vascular disease.